Link motion retracting blade switch



July 8, 1941. T. F. JOHNSON LINK MOTION RETRACTING BLADE SWITCH Filed Aug. 29, 1940 2 Sheets-Sheet 1 .0 WW H o 0 G G T 0 1.: m\ w unw umlw mi iw ww July 8, 1941. T. F. JOHNSON 2,248,876

LINK MOTION RETRACTING BLADE SWITCH Filed Aug. 29, 194G 2 Sheets-Sheet 2 Patented July 8, 1941 EJNETED STATES PATENT GFFICE f". V 2,248,876 i Y LINK MOTION RETRACTING LAD swrrCn f M TomlinsonF. Johnson, Atlanta, Ga. 2 Application August 29, 1940, Serial No- 3543167; 1

(01. 200mm) Y 1 1 Claims.

' This invention relates to high tension electrical switches and, among other objects, aims to provide a greatly improved link motionfor air-break,

retracting and swinging switch blades so 7 arranged as to cause the blade to lean backwardly beyond its vertical position, when opened, to prevent it from falling closed. A further aim is to provide link mechanism cooperating with a crank on a rotating "insulator arranged to provide a maximum mechanical advantage when finally closing and initially opening the blade with the crank near its dead center, thus making it possible to use heavy contact pressure. Still another aim is to'provide a switch which will stand openby gravity and requiresfar less effort to= Fig. 3 is a fragmentary longitudinal sectional view showing the switch in partly open position; J

Fig. 4 is a View similar to Fig. 3 but showing 'the switch in fully open position;

Fig. 5 is a sectional view taken on the line 5- of Fig. l;

i Fig. 6 is a fragmentary sectional view taken on the line 66 of Fig. 1; and

Fig. 7 is a sectional view taken on the line 1;1 of Fig. 4.

Referring particularly .to the drawings, the type of switch selected for illustrative purposes is shown as being mounted on the usual channel support and a pair of stationary insulators H and I2. It is designed to be operated by an ordinary rotatable insulator l3 carrying a crank arm [4. Such switches are usually mounted in gangs or multi-phase units and all of them are adapted to be operated by well known mechanism connected to an operating crank [5 on each" rotatable insulator.

In this instance, the stationary insulator I2 carries the usual cap or conductor terminal l6 on which is mounted a powerful spring j aw ll fwhich isclosed at the top to prevent ice from jamming the blade. The jaw also carries the usual arcing horn [8. A tubular switch blade I9 .is'carried by a cast metal arm 20 and is adapted 1 to be moved endwise into and out of contact with 'the spring jaw. Obviously, the blade and arm somewhat shorter than the front links 26.

may be madeintegral, if desired. The arm 20 is connected at its rear end to a compound linkage or series. of links. mounted on the insulator II and so arranged as to impart initial and final substantially straight line movement and intermediate swinging movement to the blade. The blade is operated by the crank arm [4 through a double jointed, connecting rod 2i which is connected at its forward end to an upstanding lug or ear..22 on the blade arm 20 in front of the link connections. The forward portion of the arm 20 carries the usual arcing conductors coacting with the horn l8.

Referring now to the link motion, the insulator H is shown as carrying a bracket 23 having an upstanding front ear 24 and a pair of rear cars 25 extending slightly above the level of the front ear 24. A pair of links 26 is pivotally mounted on'a pin 21 extending through the ear 24 and pivotally connected to a pin 28 on the blade arm behind the lug 22. This pair of links extends forwardly at an acute angle to the horizontal whenthe switch is closed. A second pair of shorter links 29 is shown as being pivoted on a pin 30 in the rear ears 25 and pivotally connected bya pivot pin 3| to a pair of short links 32 which, in turn, arepivoted to the rear end of the blade arm 20 on a pin 33. The links 26 and the double compound or jointed links 29-32 coact with the rear end of the blade arm to impart a motion simulating parallel movement; although the rearcompoundyor jointed links 29-32 are The links 26 and 29 are further connected to each other by substantially horizontal pairs of spaced links 34 pivoted on pins'35 and 36 respectively to maintain the generally parallel relation when movement is initially and finally imparted to the blade and to prevent the link system from collapsing.

A pair of brace arms 31 is shown as being integrally connected to the bracket 23 and extend rearwardly and upwardly at an angle, their rear ends being suitably secured to forwardly extending arms -38 ona plate member 39 carrying the other conductor terminal 40. This serves as a brace between the stationary insulator and the rotatable insulator to relieve them of excessive strains. i

The crank arm M, upon initially rotating insulator l3, imparts. retracting movement to the blade with the most powerful leverage, having its greatest mechanical advantage when moved from its dead center position. The tip of the blade is retracted approximately in a straight line until it clears the contact or jaw, because the links have substantially parallel movement until the whole link system has swung rearwardly slightly less than 90 or just before reaching the position shown in Fig. 3. The generally parallel movement is arrested, however, when the lower rear edge of the blade arm strikes a spacer or connecting member 4| between the lower ends of the short links 32, thus breaking the stiff leg joint between the links 29 and 32. Continued movement through only a slight angle, causes the rear edges of the links 26 to strike the ears 25 as shown in Fig. 3. Further movement to the fully opened position will cause the blade l9 to swing upwardly and rearwardly about the pivot pin 28; while the rear end of the blade arm 20 swings downwardly and forwardly, finalpivoted on the blade supporting insulator behind the first pair; a pair of short links pivotally connecting said second pair of links to the rear end portion of the blade; connecting links between said first mentioned and second mentioned pairs of links, the arrangement of said links being such as to impart both retracting and swinging movement to the blade through an angle of more than 90 and operating means connected to the blade.

2. In a high tension switch of the character described, a pair of spaced supporting insulators; a contact member on one insulator; a switch blade; a pair of spaced links on the other insulator pivoted to the blade and extending forwardly at an angle; a second pair of links pivoted on the blade supporting insulator behind th'e first pair; a pair of short links pivotally conly bringing the compound links -29--32 and con- I necting links 34 to the positions shown in Figs. 4 and 7, in which position the connecting links 34 have imparted a slight lifting or .counterclockewise movement to the arrested forward link126.

The rear end of the blade arm strikes. the pivot pin 30 between the rear ears and stops in a position slightly beyond the vertical (Fig. 4), so that it will remain open by gravity and will have no tendency to fall closed. It will be noted by comparing Figs. 1 and 4 that when the blade is moved from closed to open position, the links 25 are rotated through more than 90; the links 29 through more than 180 and the links.32 through approximately 180 relative -to links 29, but in the opposite direction. Incidentally, the links 32 are curved to clear thepivot pin 36 in this position. When t'heblade is in lthis position, the crank arm 14 is approximately 180 or less from its dead center positionsh'ownin Fig. 2, depending upon the length of the crank arm. Obviously, very little power isrequired to start the blade toward its closingposition.

In fact, it will fall by gravity after ithas been pushed forwardly beyond the vertical position. As the. blade approaches its closing position, the mechanical advantage of the crank is approaching a maximum which is required to force the bladetip forwardly into the contact or jaw.

From the foregoing description, it will be seen that the improved link motion is very simple and easy toassemble. It provides for maximum mechanical advantage in initial opening and :final closing movements of the switch and lends itself very readily to crank actuation. The blade arm is maintained stable in the open position by virtue of swinging more than 90 or beyond its vertical position and the amount of opening movement can be controlled by the link design. Since the rear end of the blade arm never swings within the confines of the link system, an ordinary sleet hood (not shown) may be secured'to-the arm .to protect the link joints in climates .requiring such hoods.

Obviously, the present invention is 'not restricted to the particular embodiment. thereof herein shown and described. Moreover, it is not indispensable that all the features of themvention be employed conjointly, since they may be employed advantageously in various combinations and sub-combinations. What is claimed is: .:i". 1. In a high tension electric .switch :of the character described, a pair of spaced supporting insulators; a contact member on one insulator;

a switch blade; a pair of spaced'links on the other insulator pivoted to the blade and, extending forwardly at an angle; a second pair of links'f necting said second pair of links to the rear end portion of the blade; connecting links between said first mentioned and second mentioned pairs of links, the arrangement of said links being such as-to impart both retracting and swinging movement to the blade through an angle of more than a rotatable insulator carrying a crank arm behind the end of the blade; a connecting rod connecting said crank to the blade above and in front of the pivotal connection of the first pair of links, said crank arm and connecting rod lying substantially in the planeof movement of the blade when the switch is in closed position. I I

3. In a high tension electric switch of the character described, a pair of spaced supporting insulators; a jaw on one insulator; a retractable switch blade; a bracket on the other insulator; a pair of forward links pivotally connected to the bracket and to the blade; compound links pivotally connected to each other and connecting the rear end of the blade to the bracketand arranged substantially parallel with the forward links; a pair of spacer links pivotally connecting the forward links to the compound links and arranged substantially parallel to the blade, the arrangement being such that initial retracting and final swinging movements are imparted to the blade to open it through an angle of more than 90; and means connected to impart opening and closing movement to the blade.

4. In a high tension electric switch of the character described, a pair of spaced supporting insulators; a jaw on one insulator; a retractable switch blade; a bracket on the other insulator; a pair of forward links pivotally connected to the bracket and to the blade; compound links pivotally connected to each other and connecting the rear end of the blade to the bracket and arranged substantiallyparallel with the forward links; a pair of spacer links pivotally connecting the forward links to the compound links and arranged substantially parallel to the blade, the arrangement being such that initial retracting and final swinging movements are imparted to the blade to open it through an angle of more i than 90; a rotatable insulator behind the second mentioned insulator; a crank arm carried by the rotatable insulator; a double jointed link connecting the crank arm to the blade in advance of and above the pivotal connection of the forwardpair of links to the blade, said crank arm lyingsubstantially in the plane of swinging movement of the blade or at its dead center when the switch is closed.

5. In a high tension electric switch of the '-character described, a pair of vertical, .spaced supporting insulators; a-jaw on one insulator;

a retractable blade; a system of links on the second insulator connected to operate the blade including spaced substantially parallel link members and connecting links therebetween; one of said parallel link members being connected to the rear end of the blade by a pair of short links to control the swinging movement of the blade; a rotatable insulator behind said second insulator; brace means between said second insulator and said rotatable insulator; a crank arm on the rotatable insulator projecting forwardly toward the rear end of and substantially in the same vertical plane as the blade when it is in closed position; and a double jointed connecting rod between the crank arm and the blade to impart opening and closing movements thereto.

6. In a high tension electric switch of the character described, a pair of spaced supporting insulators; a jaw on one insulator; a horizontally retractable and vertically swinging switch blade; a metal bracket on the second insulator; front and rear links pivotally connected at spaced points both to the bracket and to the rear end portion of the blade; spacer links pivotally connecting the front and rear links intermediate their ends; said rear links being jointed to permit the blade to be initially retracted and then swung vertically to a position beyond the vertical; and means connected to impart opening and closing movement to the blade.

7. In a high tension electric switch of the character described, a pair of spaced supporting insulators; a jaw on one insulator; a horizontally retractable and vertically swinging switch blade; a metal bracket on the second insulator;

front and rear links pivotally connected at spaced points both to the bracket and to the rear end portion of the blade; spacer links pivotally connecting the front and rear links and arranged between the blade and the bracket; said rear links being jointed to permit the blade to be initially retracted and then swung vertically to a position beyond the vertical; a rotatable insulator; brace means connecting said second insulator to the rotatable insulator; a crank arm carried by the rotatable insulator; and a double jointed connecting rod connecting the crank arm to the blade in front of and above said link system.

8. In an electric switch of the character described, a pair of supporting insulators; a jaw on one insulator; a bracket on the other insulator; a retractable switch blade; a front link pivotally connected to the bracket and to the blade; a rear compound link pivotally connected to the bracket and to the blade; a spacer link connected between the intermediate portions of the front and rear links; and means connected to impart opening and closing movement to the blade.

9. In an electric switch of the character described, a pair of supporting insulators; a jaw on one insulator; a bracket on the other insulator; a retractable switch blade; a front link pivotally connected to the bracket and. to the blade; a rear compound link pivotally connected to the bracket and to the blade; a spacer link connected between the intermediate portions of the front and rear links; means connected to impart opening and closing movement to the blade; a rotatable insulator mounted behind the rear end of the blade; a crank on the rotatable insulator; and a double jointed connecting rod between the crank and the blade, said crank lying substantially in the plane of movement of the blade or at its dead center when the blade is in its closed position.

10. In an electric switch, a support; a switch blade; front and rear links pivotally connected at spaced points to the blade and to the support and forming a quadrilateral therewith; a spacer link connected to the intermediate portions of the front and rear links, said rear link being jointed to permit the blade to be swung to a stable open position.

11. In an electric switch, a support; a switch blade; front and rear links pivotally connected at spaced points to the blade and to the support and forming a quadrilateral therewith; and a spacer link connected to the intermediate portions of the front and rear links, said front link being rotatable through more than said rear link being formed of two jointed sections arranged to swing through approximately relative to each other to permit the blade to be swung to a stable open position.

TOMLINSON F. J OHNSON'. 

